I want to know the LO frequency range of ad8342, can anyone help me?
Thanks very much!
The typical LO frequency range of AD8342 is around 3GHz.
Thanks your help!
So I want to use the AD8342 as down converting mixer,
and the RF frequency range is about 950MHz to 2150 MHz,
using the high LO, IF is about 800MHz.
Is that OK?
I think the frequency range you provide should be fine for AD8342. You could refer to Figure 53 and Figure 54 in the datasheet, if you are looking for typical performance characteristics at higher frequencies. There might be one thing we need to pay attention to. At higher frequencies, the series capacitor at the LOIN may require a relatively smaller capacitance in order to cancel out the bondwire inductance inside for good impedance matching.
Thanks for your help about ad8342.
Now I have new problem about the RF input impedance matching.
The frequency range of RF input is 950MHz-2150MHz, then I use the matching ciruite as Figure 53.
But the VSWR is above 4 at most frequency, so can you help me about this？
I think first we may need to make sure that the eval board is correctly modified according to the schematics shown in Figure 53. The 100 ohm resistor at the RF port is placed across RFCM and RFIN pins. This is different from the original eval board you ordered. If it is soldered down correctly, I believe it can be adequate for broadband matching. I got a chance to test it in the lab, the return loss at the RF port should be around -10 dB across a wide frequency range up to 3GHz. There might be some degradation at high frequency side, but it should be good for most portions in that frequency range.
Also, please make sure that the transformer used at the IF port can function well at 800MHz, because the default one on eval board is TC2-1T. It is supposed to be used below 300MHz. Much higher insertion loss will be introduced if it is used beyond that frequency range.
Hope you find above information helpful.
Thanks so much for your help.
I use the transformer works up to 1000MHz, so I thinks its good.
But I find something else that AD8342 has the EXPOSED PAD.
In the Table of PINs, there is nothing about it, and I made a mistake that I didn't connect it to the ground.
Is this bad for the impedance matching?
I do not expect disconnection of the exposed GND will change the input impedance too much, but I am not very sure. You probably need to check the whether each pin is soldered down well. Also, if you find return loss does not satisfy your requirement, extra matching network might be needed at the RF port for a specific frequency range of interest. You could follow the instructions in the datasheet on page 15.
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